Apparatus for molding hollow plastic articles

Abstract

A method and apparatus of making hollow plastic articles are disclosed in which the preforms or other articles are sequentially molded from a continuous stream of plasticized resin supplied by an extruder. The preforms are formed sequentially in a plurality of molds and immediately transferred from the molds to blowing apparatus where they are blown into plastic articles. The molds are disposed in sets of two or more molds each, and the number of blowing apparatus units is equal to the number of sets of molds, with at least two sets of molds being provided. After the preform is formed in one mold of a set of molds, it is transferred while it is still hot to the corresponding blowing apparatus for that set while the extruded stream of plasticized resin is fed into the other molds to form other preforms. The method continuously utilizes the stream of plasticized resin from an extruder and provides the most efficient use of blowing apparatus by providing a number of blowing stations less than the number of total preform molds. The method also results in energy efficiency and avoids plastic degradation by minimizing the length of time at which the plastic resin is at an elevated temperature.